Reason #1 was "It just works".
Oh yes. Macs are lovely when this is actually true...
Thanks to Bill Gates that would make a Mac really exceptional.
Actually Windows does a pretty good job trying to run on the antiquated piece of crap architecture (by todays standards) that is a PC. Compare to Linux. Have a look at some of the Max related threads in the Linux forum. I assume this is standard affair for Linux users.
Mac benefits greatly by the fact that Apple controls the hardware, therefore Apple does not have to provide reliability drivers for 99% of unknown hardware combinations in existance.
When Apple hits Intel and people have hacked/cracked OSX to get it to run on a normal PC box (not an Apple modified PC box) the same problems will pop up (or, more likely, unsupported hardware).
My Mac one or two minutes (if not less) to start up and only a few seconds to turn off.
More likely that it takes 1 or 2 seconds to Sleep. Apple do not believe in turning off. Having a blackout/turning off mains in your standard 'oh, it's apparently off, it says it is' mode can be disastrous in a vmem managed environment.